Author: Chris

This is the third and final part of my whistle-stop tour of IS-IS, for people studying for their Juniper JNCIS-SP and JNCIS-ENT exams. In this post, we learn how to troubleshoot IS-IS. Are you wearing your safety hat? Then, let’s go!

In Part 2 we take a deeper-dive into IS-IS. We do packet captures of LSAs, we look at the metrics, the Designated Intermediate-System, and we even explore our feelings together, so that we can finally find inner-peace with ourselves. Great!!!

Here’s the first of our three-part beginners guide to IS-IS. We’ll compare it to OSPF; we’ll talk about Level 1 and Level 2; we’ll explain the bizarre addressing system; we’ll look at a basic config, and we’ll talk about why Googling for IS-IS is very different from Googling for ISIS.

In the 90s, the big fashion was Tamagotchis. In 2017 it was fidget spinners. And of course, in 2018 there’s only one trend on everyone’s lips: route summarisation. In Junos there’s three ways to summarise routes. Want to know what they are? Well gosh damn, you’ve come to the right place!

Want to learn how to configure Chassis Cluster, which lets you configure high-availability failover on Juniper firewalls? Good luck with the official documentation – it weighs in at precisely 638 pages long. 638 pages! That’s the length of two good books! Or one badly edited one. Anyway, this article is my attempt at boiling those 638 pages down into something a bit more manageable. You can thank me by emailing me £700,000.

Once you’ve read my guide to the new link-state advertisement types in OSPFv3, give this post a read, where we take a deep-deep into the OSPFv3 database. Put your topology hat on: we’re going exploring.

When I first heard that OSPFv3 introduced even more link-state advertisement (LSA) types, I despaired. As if the original seven didn’t take us long enough to memorise! Then I actually learned what they do – and honestly, it’s hard to imagine why we ever did it any differently. Let’s learn about them together!

There’s two handy Cisco troubleshooting tips I’ve learnt during my time as a network engineer. The first is to just ignore a problem and go to the pub. The other tip is the debug condition command, which helps you to troubleshoot by limiting debug messages to certain interfaces, IP addresses, MAC addresses, and a whole lot more.

A little while ago, I was mucking about with some EIGRP authentication in a lab. Because when I party, I party hard. Rock and roll is an integral part of my soul. Anyway, EIGRP was running. Neighbors were formed. And then I added a keychain, and applied it to my interfaces. The neighborship dropped, tried to re-establish – and failed. Why? Let’s find out!

I’m Chris, a network engineer from London. This is a blog of random knowledge I’ve acquired while studying for some sweet sexy network engineering certifications. Technically vendor neutral, but as you’ll soon find out, I love Junos very much.

As I learn cool new stuff, I try to write it up with plenty of jokes, and a generous dollop of silliness, so that you’ll have as much fun learning about networking as I do.